package com.company;

/**
 * @author zhf
 * @date 2021/10/18
 */

/**
 * 合并两条有序单链表
 */
public class TwoSingleLine {




    /*
    定义单链表；
     */
    public class ListNode{
        int val;
        ListNode next;
        ListNode(){};
        ListNode(int val){this.val = val;}
        ListNode(int val,ListNode next){
            this.val = val;
            this.next = next;
        }

    }


    public static void main(String[] args) {
    }
    //头插法创建链表；

    public void  addNode(int data){
        ListNode first = new ListNode();
        ListNode s = new ListNode(data);
        s.next = first.next;
        first.next = s;
    }
    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
        ListNode head = new ListNode();
        ListNode pre = head;
        if (l1 == null){
            return l2;
        }
        if (l2 == null){
            return l1;
        }
        while (l1!=null&&l2!=null){
            if (l1.val <= l2.val){
                pre.next = l1;
                l1 = l1.next;
            }
            else {
                pre.next = l2;
                l2 = l2.next;
            }
            pre = pre.next;
        }
        if (l1 == null){
            pre.next = l2;
        }
        if (l2 == null){
            pre.next = l1;
        }
        return head.next;
    }
}
